Although "The Gallant Pelham" served the entire war with the artillery, he was destined to fall while moonlighting in a cavalry charge.

A native Alabamian, he withdrew from West Point upon the outbreak of hostilities and joined the Confederate army. His assignments included: lieutenant, Wise (Va.) Artillery (early 1861); captain, Stuart Horse Artillery (March 23, 1862); major, Artillery (August 9, 1862); lieutenant colonel, Artillery (April 4, 1863, to rank from March 2); and commanding Horse Artillery Battalion, Cavalry Division, Army of Northern Virginia (August 1862-March 17, 1863).

After fighting at lst Bull Run, he became the captain of the first horse artillery battery that served with JEB Stuart, becoming close friends with the general. Commanding his unit, he saw action at Yorktown and during the Seven Days. Promoted, he commanded all of Stuart's horse batteries at 2nd Bull Run and Antietam. At Fredericksburg he held up the advance of a Union division against the Confederate right with only two guns. With only one gun left, he continued to shift positions despite the fact that 24 enemy guns were now concentrating their fire on him. Disobeying repeated orders to withdraw, he only did so upon running out of ammunition. General Lee observed and said, "It is glorious to see such courage in one so young!"

Known as the "Boy Major," he heard of an impending action at Kelly's Ford on March 17, 1863. Away from his battalion at the time, he joined the fray with the cavalry. He fell victim to a shell fragment while directing a column past a fence. Thought to be dead, he was thrown over a horse and led from the field. Quite a while later he was lowered to the ground and found to be still alive. He died shortly thereafter. Some believed that prompt attention might have saved his life.